The mixture was incubated for 20 min. at 500C. Then 2.5 ml TCA (Trichloroacetic acid,10%) was added to each mixture and these were centrifuged for 10 min. at 3000 rpm. Then 2.5ml of the upper layer was mixed with distilled water (2.5 ml) and 0.5ml FeCl3 (0.1%)